The invention relates generally to a photolithography method for making a semiconductor device, for example, a diode containing nonvolatile memory array.
One prior art process using a hard mask stack shown in FIG. 1A can be used to fabricate 45 nm and 80 nm features. The stack consists of a layer of organic hard mask 103, also known as an amorphous carbon advanced patterning film (APF), a layer of Dielectric Anti-Reflective Coating (DARC) 106, such as silicon oxynitride, on top of organic hard mask 103, and a Bottom Anti-Refection Coating (BARC) 109 layer, such as an organic BARC layer, on top of DARC layer 106. A photoresist 111 can be coated above the BARC layer.